Discussion in 'Supporting Physics' started by Paul, Sep 14, 2018.
anyone done these? I don't have microphones for my dataloggers either...
You are a bit hampered by the lack of microphones otherwise follow the instructions.
Works well with microphones, might be worth investigating using mobile phone as a microphone if you can manufacture a connection to datalogger.
Found a unilab kit BNIB, told the teacher it's a demo at best, teacher not happy. oh well
(the 2 specialist physics teachers last year never went near it.)
For the speed of sound in air I use ordinary microphones (about 1m apart) connected to our Picoscope (PC oscilloscope) in single trigger mode.
We have never done the speed in a solid.
This is what I use our Unilab Fast timer for, we hit a long metal rod (hammer electrically connected, which starts the clock as it hits the rod) and an amplified microphone (which we buy anyway) generates enough voltage to stop it.
We have the Dataharvest stethoscopes for this one, but the teacher who used that method left a couple of years ago. I think they currently use the gym wall, though what we'll do next year when the gym extension is being built I don't know
If (and i know its a big if) your school has ipads or allows your students to use mobile phones in lessons. See if there is a free app out there that can take the measurements for you.
we use the unilab kit but only have one. Speed of sound is done out on the field with the watcher with the stopwatch starting when they see two wooden blocks hit together and stopping when they hear it. If raining we use the Kundt's tube I made, though we don't call it that.
The unilab kit (timer and 2 crystal microphones) worked great, well once you take it apart and find it needs a battery.
Piezo sounders work well as contact (stethoscope) microphones for speed of sund in solids. They are cheap on ebay/amazon or you can do as I did - take them out of stopwatches and solder leads on. Gaffer tape them onto the material you are using.
Some of the commercial ones are just a pair of earbud headphones embedded in a lump of metal (to keep them on the material).
If you can find a PC with a genuine stereo microphone input you can plug earbuds in and use Audacity to get a trace and see the time between pulses when you hit one end of the material. Moulding a big lump of plasteceine around the earbud would probably work to hold it on the material.
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